Submergible liquid pump

ABSTRACT

A submergible liquid pump is provided with a leakage-collecting chamber arranged around the drive shaft. The leakage-collecting chamber is defined by a stationary wall and by a wall rotating with the drive shaft. Leakage hurled outwards during operation of the pump is collected with a means arranged in the leakagecollecting chamber and thus removed from the leakage-collecting chamber.

United States Patent 1191 Navelsaker Au 5, 1975 [54] SUBMERGIBLE LIQUIDPUMP FOREIGN PATENTS OR APPLICATIONS lnvemori Olav RasmflssonNavelsaker, 24,985 1907 United Kingdom 415/89 Nordengveren, Norway915,046 8/1954 Germany 277/25 [73] Assignee: Thune-Eureka A/S, Oslo,Norway [22] Filed: Feb 5 1974 Primary E.\'amfner-Henry F. RaduazoAttorney, Agent} or FirmYoung & Thompson [21] Appl. No: 439,765

[30] Foreign Application Priority Data [57] ABSTRACT July 5, 1973 Norway2766/73 A submerglble lrquld pump 1s provlded w1th a leakage- [52] us CL415/111; 415/168. 277/25. collecting chamber arranged around the driveshaft.

415/89 The leakage-collecting chamber is defined by a sta- 51 Int. Cl.F0ld 25/32 tionary and by a rotating with the drive Shaft [58] Field ofSearch 277/25; 415/111, 169 A, Leakage hurled outwards during 0106mm415/89 168 pump is collected with a means arranged in theleakage-collecting chamber and thus removed from the [56] ReferencesCited leakage-collecting chamber.

UNITED STATES PATENTS 1/l974 Lewis 4l5/89 4 Claims, 1 Drawing FigureSUBMERGIBLE LIQUID PUMP The invention relates to a submergible liquidpump having a leakage-collecting chamber arranged around the driveshaft.

In such pump units, which are generally utilized onboard ships, thesealing for the hydraulic oil is, as a rule, a mechanical sealing ofextremely good quality. The sealing operates under ideal conditions withcontrolled oil circulation which means substantially zero leakage and alifetime of several years of continuous operation. Any oil leakage isconveyed by a throw-off ring on the drive shaft to a separateleakage-collecting chamber which can receive substantially more oil thanthe amount possibly leaking from bearing housing and stationaryhydraulic motor. By means of a neutral pressure gas, the leakage in theleakage-collecting chamber can be transported from theleakage-collecting cham' ber and, for example, up to the deck of theship.

The object of the present invention is to improve the sealingarrangement in pumps of the type described introductorily, and also toachieve an automatic trans port of leakage to the deck.

In accordance with the invention, this is achieved in that theleakage-collecting chamber is formed as a rotary leakage-collectingchamber in that it is defined by a stationary wall and by a wallrotating with the drive shaft. During operation of the pump, any leakageis then hurled outwardly in the leakage-collecting chamber and can becollected by a means arranged in the leakage-collecting chamberconnected to a conduit which, for example, can lead up to a vessel ondeck. When the pump is operating, any leakage is hurled out bycentrifugal force, and forms a ring outermost in the leakage-collectingchamber, at a pressure sufficient to press the leakage up to, forexample a vessel.

The wall rotating with the drive shaft in the leakagecollecting chambercan be formed as a separate element mounted to the drive shaft; however,when concerned with a centrifugal pump, it can to advantage be formed bythe impeller of the pump.

The means for collecting leakage hurled out during operation can be apick-up valve. The said pick-up valve may be combined with a check valvefor expelling leakage during standstill by means of a neutral pressuregas supplied to the leakage-collecting chamber.

According to the invention, therefore, a valve unit is provided whichcomprises two check valves having a common spring but having greaterseat diameter for the check valve used during standstill whenthe leakageis expelled by means of a neutral pressure gas. When theleakage-collecting chamber is subjected to gas pressure, the combinedvalve permits any oil leakage to be transported from the bottom of theleakage-collecting chamber through the largest check valve and upthrough an oil leakage tube. The opening pressure for the smaller valveis greater, due to the common spring and due to the difference in seatdiameter, such that the gas pressure cannot escape this way, that is tosay through the actual pick-up valve. During operation, the dynamicpressure of the leakage ring drives the leakage through the smallervalve, the larger valve'remaining sealed, and also in this case theleakage will be trans ported to the deck, on the action of the dynamicpressure.

The leakage-collecting chamber is utilized preferably together with aso-called pressure chamber formed in the bearing housing above theleakage-collecting chamber, in that the wall rotating with the driveshaft, or the impeller, respectively, are provided with an extension inthe form of a collar projecting upwards and into the chamber around awall therein, to form a rotation slot between the leakage-collectingchamber and the pressure chamber.

Preferably, a check valve is arranged in the communication between thepressure chamber and the leakage-collecting chamber, the said checkvalve being open during operation of the pump.

The invention is further explained hereinbelow by means of an embodimentexample illustrated on the FIGURE.

The FIGURE illustrates a section through a submergible pump. Theessential components illustrated are the bearing housing 24, the driveshaft 20, the impeller 27 mounted on the drive shaft in the pump, andthe inlet housing 33.

The drive shaft 20 is mounted in the bearing housing 24 by means of ballbearings 22 and 23. The drive shaft 20 means from the hydraulic motor 21indicated.

The impeller 27 together with the bearing housing 24 define aleakage-collecting chamber 26.

The leakage-collecting chamber can, of course, also be limited by aseparate part which is mounted on the drive shaft and rotates therewithand does not constitute any part of the impeller, which may be the casewhen the suction opening of the impeller faces upwardly, or where aso-called two-way impeller is concerned. The modifications thennecessary in the construction are so obvious to a skilled person and arenot further illustrated or described therefore.

A pressure chamber 28 is formed in the bearing housing above theleakage-collecting chamber 26. The upper collar 29 of the impeller 27extends into the pressure chamber 28 and widens gently upwardly andoutwardly. The collar 29 is provided with transport threads 30 whichface in towards the rotation slot 31 formed between the collar 29 andthe bearing housing 24. The pressure chamber 28 is defined at the bottomthereof by the upper wear-ring 32 of the pump.

The inlet housing 34 is provided with a casing 33 facing downwardlytoward the cargo, said casing forming a pre-compression chamber 34. Thesaid precompression chamber is in communication with the pressurechamber 28 by means of openings 35.

Neutral pressure gas is supplied to the leakagecollecting chamber 26through a conduit, not shown. The pressure chamber which is disposedcylindrically around the upper collar 2 of the impeller, is subjected topressure when the pump is submerged in the cargo, leakage occuringthrough the wear-ring slot and through the openings 35 from apre-compression chamber 34 formed by a casing 33. The said openings havea double function: primarily as side channels for the wear-ring leakageand secondarily as pressure openings between the pre-compression chamberand the pressure chamber. When the pump is submerged in the cargo, thecargo rises rapidly to the wear-ring 32 internally. In theprecompression chamber 34, the air is then subjected to a certain liquidpressure. This pressure is transmitted to the pressure chamber since theliquid flows more slowly through the wear-ring slot than the air flowsin from the compression chamber. When the liquid or cargo level is inbalance, it will be at a lower level in the pressure chamber than if theprecompression chamber effect had not been present. In this manner, thegreatest possible gascontacted surface on the impeller is achieved, suchthat the disc-loss is reduced to a minimum even of the neutral gas isnot utilized. Obviously, this effect can also be achieved when aseparate, completely rotating wall is utilized for defining theleakage-collecting chamber.

The inner, outwardly widening impeller collar 29 which is provided withtransport threads represents an extra safety arrangement which comesinto force if the pump should inadvertently be disposed in horizontalposition for a period of time. The transport threads counteract thepenetration of cargo and when the pressure is in balance over the slot,gas will not flow out if liquid cannot penetrate. Oil leakage willautomatically be transported to the deck, also in this position.

In the slot between the impeller collar 29 and the bearing housing 24 acheck valve 36 is arranged which includes an annular sealing lip madefrom a resilient material and has self-lubricating properties and is ofsufficient hardness and density for the purpose. The sealing lip may becircular or may be divided into segments which do not necessarily needto seal against one another. During standstill, that is to say, when theshaft is stationary, the sealing lip 10 is maintained pressed againstthe inner cylinder surface in the slot, i.e. against the bearing housing24, by means of a surrounding endless helical spring 11. The helicalspring is arranged in a groove 12 in the collar 29. The spring may beprovided with ballast, either in the form of an internal endless tubefilled with lead (shot or granulate) and of suitable reciliency, or inanother manner. Axially opposing the lip 10, the sealing element isformed to seal against the outer rotary portion, i.e. against theimpeller collar 29, in this case by means of the O-ring 8 indicated. Thewhole sealing arrangement is adapted such that the sealing lip andspring are capable of moving radially on the action of the centrifugalforce when the impeller rotates, whereby the valve is in open position.

From the bottom of the leakage-collecting chamber 26, an oil leakagetube 9 leads up to a check valve 41. From there, a bore leads up furtherthrough the bearing housing. The said bore 25 is connected, in mannernot illustrated, to a conduit which leads up to a vessel on deck.

During standstill, neutral gas may be supplied through a conduit (notshown) to the leakagecollecting chamber 26 and any oil leakage presentin the leakage-collecting chamber is then forced out through the bore 9,the check valve 41 and up through the bore 25 to a vessel on deck.

When the pump is in operation, any leakage will be hurled outwardly bycentrifugal force in the leakagecollecting chamber and forms a ringoutermost in the leakage-collecting chamber, at a pressure which issufficiently great to press the leakage to a vessel on deck, through acheck valve 37. The said check valve 37 is, through a bore 42, incommunication with a bore 40 which faces towards the liquid flow. Whenthe pressure of the oil leakage ring is sufficiently high, the checkvalve 27 opens and the leakage may then flow up through the bore 25 to avessel on deck.

The two check valves 41 and 37 are, as illustrated, assembled as a unitand have a common spring 43. The inner check valve 41 has a larger seatdiameter than the outer check valve 37. When the leakage-collectingchamber is subjected to gas pressure, during standstill, the arrangementpermits any leakage to be conveyed from the bottom of theleakage-collecting chamber through the inner check valve 41 and up tothe deck; the opening pressure of the outer valve 37 being greater dueto the common spring 43 and due to the difference in seat diameter, sothat the gas pressure cannot escape this way. During operation, thedynamic pressure of the leakage ring drives the leakage through theouter check valve 37, the inner check valve 41 then remaining sealed,and the leakage is therefore conveyed to the deck.

The invention is hereinbefore described in connection with a specificembodiment but is, of course, not restricted thereto. As alreadymentioned, the rotating wall of the leakage-collecting chamber can be anelement which is independent of the impeller, and the construction isthen modified as necessary.

Having described my invention, I claim:

1. A submergible liquid pump having a leakagecollecting chamber arrangedaround a drive shaft of the pump, said leakage-collecting chamber beingdefined by a stationary wall and by a wall rotating with the said driveshaft, means in the said leakage-collecting chamber for removingcollected leakage hurled outwards in theleakage-chamber during operationof the pump by said rotating wall, a bearing housing for the said driveshaft, the said bearing housing defining the said stationary wall, apressure chamber in the said bearing housing extending around the saiddrive shaft above the said leakage-collecting chamber, which pressurechamber is downwardly exposed, an extension in the form of a collarprojecting upwardly from the said wall rotating with the drive shaft andinto the said pressure chamber, the said collar being adjacent a wall ofthe said pressure chamber thereby forming a rotation slot between thesaid leakage-collecting chamber and the said pressure chamber, and apre-compression chamber in the form of a downwardly open easing intowhich said pressure chamber opens.

2. A submergible pump as claimed in claim 1, and a check valve in saidrotation slot, said check valve being opened during operation of saidpump.

3. A submergible pump as claimed in claim 1, said liquid pump comprisinga centrifugal pump with an impeller, said wall rotating with the driveshaft comprising a part of said impeller.

4. A submergible liquid pump having a leakagecollecting chamber arrangedaround a vertical drive shaft of the pump, said leakage-collectingchamber being defined by a stationary wall and by an upwardly extendingwall rotating with the said drive shaft, means in the saidleakage-collecting chamber for removing collected leakage hurledoutwards in the leakagechamber during operation of the pump by saidrotating wall, said stationary wall and said rotating wall defining apassage which leads from the lowest part of the said leakage-collectingchamber, a first check valve in said means and, a second check valve inthe said means, and a common spring for the two said check valves, saidfirst check valve having a greater valve seat diameter than said secondcheck valve.

1. A submergible liquid pump having a leakage-collecting chamberarranged around a drive shaft of the pump, said leakagecollectingchamber being defined by a stationary wall and by a wall rotating withthe said drive shaft, means in the said leakage-collecting chamber forremoving collected leakage hurled outwards in the leakage-chamber duringoperation of the pump by said rotating wall, a bearing housing for thesaid drive shaft, the said bearing housing defining the said stationarywall, a pressure chamber in the said bearing housing extending aroundthe said drive shaft above the said leakage-collecting chamber, whichpressure chamber is downwardly exposed, an extension in the form of acollar projecting upwardly from the said wall rotating with the driveshaft and into the said pressure chamber, the said collar being adjacenta wall of the said pressure chamber thereby forming a rotation slotbetween the said leakage-collecting chamber and the said pressurechamber, and a pre-compression chamber in the form of a downwardly opencasing into which said pressure chamber opens.
 2. A submergible pump asclaimed in claim 1, and a check valve in said rotation slot, said checkvalve being opened during operation of said pump.
 3. A submergible pumpas claimed in claim 1, said liquid pump comprising a centrifugal pumpwith an impeller, said wall rotating with the drive shaft comprising apart of said impeller.
 4. A submergible liquid pump having aleakage-collecting chamber arranged around a vertical drive shaft of thepump, said leakage-collecting chamber being defined by a stationary walland by an upwardly extending wall rotating with the said drive shaft,means in the said leakage-collecting chamber for removing collectedleakage hurled outwards in the leakage-chamber during operation of thepump by said rotating wall, said stationary wall and said rotating walldefining a passage which leads from the lowest part of the saidleakage-collecting chamber, a first check valve in said means and, asecond check valve in the said means, and a common spring for the twosaid check valves, said first check valve having a greater valve seatdiameter than said second check valve.